It is common to make hollow plastic articles such as containers by closing a mold about a heated parison and blowing the parison outwardly against the confines of the mold to form the hollow article. More recently, it has been suggested that labels can be delivered to an open mold and deposited in the cavity of the mold so that when the mold is closed and the parison is blown, the labels become adhered to and become a part of the blown hollow article.
In certain types of machines, the space for delivery of the label into the open mold is limited because of the construction of the machine. More specifically, in one type of blow molding apparatus, a plurality of sets of molds are mounted on a wheel rotatable about a horizontal axis and the molds are moved toward and away from one another to enclose a parison and the parison is then blown by application of air to the confines of the cavity between the mold sections as the wheel rotates. In such an arrangement, the space is extremely limited and the problem of placement of labels in the open mold is difficult. The blown articles are usually taken out of the blow molding apparatus adjacent the twelve o'clock position and the extruded parison is introduced at the three o'clock position such that the area during which the molds are open therebetween is limited. Where two labels are to be delivered for placement on opposite sides of the hollow article, the problem is more difficult. The problem is further complicated when the molds have plural cavities and labels are to be delivered simultaneously to the plural cavities.
In U.S. Pat. No. 4,680,000, there is disclosed and claimed a method and apparatus for applying labels in the molds of a plastic blow molding machine comprises removable labels successively from one or more magazines, depositing the labels on an endless conveyor which transports the labels to a position adjacent an open mold and laterally transferring the labels from the conveyor to a position within the molds such that when the mold closes about a plastic parison and the parison is blown, the labels become adhered to the blown plastic bottle. Such an arrangement necessitates the use of an endless conveyor interposed between the magazine and the mold sections. Accordingly, the labels must be first formed then handled and delivered into the magazine, rmmoved from the magazine positioned properly on the endless conveyor and then removed from the endless conveyor and delivered to the mold sections. These actions contribute to the possibility of loosing control of the position of the labels thereby being misaligned on the blown container especially where the labels are thin and made of plastic.
U.S. Pat. No. 4,397,625 shows a labeler utilized with a rotating blow molding machine which has pick up heads that remove labels from magazines and deliver them to the mold cavities. This arrangement also has the disadvantages of the need for placement of the labels in magazines and removal therefrom.
Accordingly, among the objectives of the present invention are to provide a method and apparatus for delivering labels between the sections of an open mold of a wheel or rotary type blow molding machine which obviates the need for magazines and conveyors thereby minimizing the likelihood of misalignment of the label; which will accommodate various size labels; and which will deliver labels to both sides of the cavity if desired.
In accordance with the invention the method and apparatus for applying labels in the molds of a plastic blow molding machine of the type wherein a plurality of sets of molds are mounted on a wheel rotatable about a horizontal axis and the molds are moved toward and away from one another to enclose a parison and the parison is then blown to the confines of the cavity between the mold sections which comprises successively die punching labels from a web onto vacuum cups and delivering the labels successively between the mold sections by moving the vacuum cups between the mold sections and thereafter moving the cups laterally into the cavities of the mold sections.